Laminate articles formed by the joining of discrete webs in a layered relationship are well known in the art. Laminate articles include laminates of dissimilar materials. The materials may be dissimilar in mechanical tensile properties, thermal properties, or visual/tactile properties. For example, a nonwoven web may be joined to a relatively stiff fabric to provide for a soft surface feel to the fabric.
The dissimilar materials may be joined by melt bonding, adhesive bonding, ultrasonic bonding, and the like. Bonding methods are often determined by the materials themselves, and often require adhesive bonding. For example, a laminate of materials having widely differing melt properties may require an adhesive layer between laminate layers. Even materials having similar melt properties, such as nonwoven and thermoplastic film materials are often joined by adhesive for adequate bonding to prevent unwanted delamination. Although adhesive may be necessary, such processing methods can be expensive due to the addition of adhesive, and the resulting laminate is often relatively stiff, depending on the laminate materials and the level of adhesive added.
Often laminate articles are intended to combine properties of the constituent layers to achieve synergistic benefits. For example, a multi-layered nonwoven laminated article could be intended for use as a substitute for a woven web such as a textile web. A web comprised of a layer of thermoplastic man-made fibers and a layer of cellulose-based fibers is known. The cellulose-based fiber layer is disclosed as thermally bonded to the thermoplastic man-made fiber layers at spaced apart locations. However, it appears that thermal bonding between all the layers is necessary to produce the requisite bonding.
EP-A-112,654 issued to Haq, et al. discloses a laminate comprising two sheets of nonwoven fabric or the like having sandwiched between them a solid core material which may be a highly porous, optionally liquid-containing, polymer. The two outer sheets are bonded to each other, without involving the core material, by means of a plurality of small, spaced bonding points, for example, spot-welds. Preferably the core material is in continuous sheet form and is perforated to accommodate the bonding points. However, it appears it would present a significant processing problem to register the perforations of the core material in order to have the outer layers bonded therethrough.
Nonwoven webs are beneficial as components of disposable consumer products, such as diapers, incontinence briefs, training pants, feminine hygiene garments, and the like, as well as in wipes such as disposable wet wipes. However, used alone, such nonwovens are limited in the range of beneficial properties, including visual, tactile, strength or absorbent properties due to the limits of known methods of making, particularly as compared to woven or knitted materials. Importantly, laminates of nonwoven webs and other materials for use in disposable consumer products have heretofore been limited due to processing limitations, including incompatible materials (e.g., thermally dissimilar materials), cost considerations (e.g., adhesive lamination costs) or tactile properties (e.g., softness and visual aesthetics).
Also known in the art is a laminate of at least three layers with the outermost layers bonded to each other through apertures formed in the center or inner layer(s) during the bonding process. Such laminates have a variety of possible properties depending upon the choice of materials for the outer and inner layers. It is possible to achieve a soft, cloth-like hand feel through the use of nonwoven outer layers, and to add absorbency by using a cellulosic center layer similar to a BOUNTY® paper towel. The continuity of the inner layer is disrupted however, because the layer is apertured at the bond sites between the outer layers.
Accordingly, it would be desirable to have laminate articles with webs of dissimilar material properties, which are not dependent upon thermal compatibility of each constituent layer for structural integrity.
Additionally, it would desirable to have a laminate article comprising both nonwoven webs and cellulosic webs.
Additionally, it would be desirable to have a laminate web formed by joining the constituent layers without adhesive.
Further, it would be desirable to have a multi-layer web combining the softness and durability of a nonwoven layer with the absorbency of a continuous cellulosic layer.